Single-centre, randomized, clinical trial of opioid-free analgesia versus routine opioid-based analgesia regimen for the management of acute post-operative pain following caesarean section: study protocol

Background: Pain management post-caesarean section is a common source of exposure to opioids in women. To address the rising opioid addiction associated with peri-operative administration, trend in operative analgesia is moving towards opioid-free, multimodal analgesia. We present our protocol for this study so that it may be replicated in other settings and possibly modified for future studies.Methods: In a Single-centre, non-inferiority, parallel, randomized, controlled, clinical trial with balanced allocation [1:1] into two arms, we compared a peri-operative opioid-free analgesia regimen with a routine post-operative opioid-based analgesia regimen in women undergoing caesarean section under spinal anaesthesia. Primary outcome measures were post-operative pain intensity at 4, 8 and 24 hours (using Numerical Rating Scale) and post-operative pentazocine use. Secondary outcome measures were the incidence of adverse events and Apgar score. Results will be published in a peer-reviewed, open access journal.Conclusions: This protocol adopted the use of intravenous paracetamol and intravenous NSAID as baseline analgesics. Magnesium sulphate was introduced peri-operatively as part of our opioid-free multimodal analgesia regimen because of its established effect in decreasing post-operative pain and opioid use. We also relied on the preventive analgesic effect of administration of intravenous paracetamol and intravenous magnesium sulphate before surgical incision, continued intraoperatively and post-operatively. In addition, magnesium sulphate is a familiar drug to the obstetrician, readily available and affordable in most settings where comprehensive emergency obstetric care is offered, easy to administer and it has been well tolerated clinically.Trial registration: This protocol was registered with clinicaltrials.gov (Identifier: NCT04539249) on September 3, 2020, prospectively.